using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace BruteForceAlgorithm

{

    class BruteForceAlgo

    {

​

        public delegate bool BruteForceTest(ref char[] testChars);

​

        public static bool BruteForce(string testChars, int startLength, int endLength, BruteForceTest testCallback)

        {

            for (int len = startLength; len <= endLength; ++len)

            {

                char[] chars = new char[len];

​

                for (int i = 0; i < len; ++i)

                    chars[i] = testChars[0];

​

                if (testCallback(ref chars))

                    return true;

​

                for (int i1 = len - 1; i1 > -1; --i1)

                {

                    int i2 = 0;

​

                    for (i2 = testChars.IndexOf(chars[i1]) + 1; i2 < testChars.Length; ++i2)

                    {

                        chars[i1] = testChars[i2];

​

                        if (testCallback(ref chars))

                            return true;

​

                        for (int i3 = i1 + 1; i3 < len; ++i3)

                        {

                            if (chars[i3] != testChars[testChars.Length - 1])

                            {

                                i1 = len;

                                goto outerBreak;

                            }

                        }

                    }

​

                outerBreak:

                    if (i2 == testChars.Length)

                        chars[i1] = testChars[0];

                }

            }

​

            return false;

        }

​

        static void Main(string[] args)

        {

            BruteForceTest testCallback = delegate(ref char[] testChars)

            {

                var str = new string(testChars);

                return (str == "bbc");

            };

​

            bool result = BruteForce("abcde", 1, 5, testCallback);

            Console.WriteLine(result);

        }

    }

}